Photonic Quantum Logic with Narrowband Light from Single Atoms

TL;DR

This paper demonstrates quantum logic with narrow linewidth photons generated from a single atom, enabling advanced quantum photonic applications like networked quantum computing and quantum sensing.

Contribution

It presents the first implementation of a controlled-NOT gate with narrowband photons from a single atom coupled to a high-finesse cavity.

Findings

Successful entanglement of photons via a photonic chip-based CNOT gate

Observation of non-classical correlations over long temporal separations

Potential for integrating narrowband photon sources with quantum photonic networks

Abstract

Increasing control of single photons enables new applications of photonic quantum-enhanced technology and further experimental exploration of fundamental quantum phenomena. Here, we demonstrate quantum logic using narrow linewidth photons that are produced under nearly perfect quantum control from a single ^87Rb atom strongly coupled to a high-finesse cavity. We use a controlled- NOT gate integrated into a photonic chip to entangle these photons, and we observe non-classical correlations between events separated by periods exceeding the travel time across the chip by three orders of magnitude. This enables quantum technology that will use the properties of both narrowband single photon sources and integrated quantum photonics, such as networked quantum computing, narrow linewidth quantum enhanced sensing and atomic memories.